Lignin carbon / silicon nanoreinforced material and preparation method and application thereof

Abstract

The application discloses a lignin carbon / silicon nano reinforcing material and a preparation method and application thereof, and the preparation method of the lignin carbon / silicon nano reinforcing material comprises the following steps: (1) performing acid precipitation on a mixed solution containing lignin or a salt thereof, a silicon source, a surfactant, alcohol and water to obtain a lignin / silicon nano composite material; the silicon source is a substance containing silicon oxide; and (2) carbonizing the obtained lignin / silicon nano composite material to obtain a lignin carbon / silicon nano composite material. The rubber reinforcing material is prepared by using cheap lignin as a main raw material, raw materials are abundant, a preparation process is simple, and the production cost of the rubber reinforcing filler can be effectively reduced; the carbon / silicon nano reinforcing material has small particle size and uniform dispersion, can significantly improve the vulcanization rate and mechanical properties of rubber, can obtain a reinforcing effect similar to that of carbon black, and has certain economic and social benefits.

Description

Technical Field

[0001] This invention relates to the field of carbon composite materials technology, specifically to a lignin-carbon / silicon nano-reinforcing material and its preparation method and application. Background Technology

[0002] Lignin is abundant in nature, ranking as the second most abundant organic compound after cellulose, and is renewable. Lignin is a complex polymer with a network structure based on phenylpropane monomers. It primarily contains functional groups such as methoxy, phenolic hydroxyl, alcoholic hydroxyl, carbonyl, and carboxyl groups. The phenolic hydroxyl group is a crucial functional group in lignin, significantly influencing its physicochemical properties (solubility and reactivity).

[0003] Lignin, with its unique network structure and high carbon content (50-60%), can be modified and effectively compounded with silica, followed by high-temperature carbonization, making it an ideal precursor for preparing carbon-silicon composite materials. However, most lignin is used for combustion and heat generation, and its utilization is not rational. Adding lignin as a carbon source to rubber to replace or partially replace traditional carbon black for reinforcing rubber would not only turn waste into treasure but also benefit environmental protection and resource recycling.

[0004] Reinforcing fillers are essential in the preparation of rubber compounds, with carbon black and silica (silica) being the most commonly used. Carbon black-reinforced rubber exhibits a higher elastic modulus, while silica-reinforced rubber has a lower rolling resistance coefficient. To combine the advantages of carbon and silicon, silicon is introduced into carbon, allowing both to disperse uniformly to prepare carbon / silicon composite fillers. When one component is more prominent, its advantages become more pronounced.

[0005] Currently, most existing technologies focus on improving the extraction methods and processes of lignin, such as Chinese inventions CN201611041135.8 and CN201611167422.3. These technologies mainly involve modifying lignin or combining modified lignin with materials such as silicon. Their preparation processes are complex, production costs are high, and the reinforcing effect is not ideal. These limitations restrict the large-scale promotion and commercialization of lignin, and most of them remain at the laboratory stage.

[0006] In view of the shortcomings of the existing technology, it is necessary to carry out research and development to provide a simple preparation process so that the carbon / silicon reinforcing filler has the advantages of small particle size, easy dispersion and good reinforcement effect, which is more conducive to application and promotion. Summary of the Invention

[0007] Purpose of the invention: The technical problem to be solved by the present invention is to provide a lignin carbon / silicon nanocomposite material and its preparation method, which addresses the shortcomings of the prior art.

[0008] A further technical problem to be solved by the present invention is to provide the application of the above-mentioned lignin carbon / silicon nanocomposite material.

[0009] To solve the above-mentioned technical problems, the present invention discloses the following technical solution:

[0010] In a first aspect, the present invention discloses a method for preparing lignin-carbon / silicon nanocomposite materials, comprising:

[0011] (1) Acid precipitation is performed on a mixed solution containing lignin or its salt, silicon source, surfactant, alcohol and water to obtain lignin / silicon nanocomposite material; the silicon source is a substance containing silicon oxide; the particle size of the lignin / silicon nanocomposite material is about 600 nm, such as 550-650 nm.

[0012] (2) The obtained lignin / silicon nanocomposite material is carbonized under inert gas conditions, cooled to room temperature, and ground into a particle size of 300-500nm to obtain lignin carbon / silicon nanocomposite material; the particle size of the lignin carbon / silicon nanocomposite material is about 500nm, such as 450-550nm.

[0013] In step (1), the lignin or its salt includes softwood lignin, hardwood lignin, alkali lignin, sulfate lignin, sodium lignin sulfonate, calcium lignin sulfonate, papermaking black liquor, or any mixture thereof; the papermaking black liquor is wastewater generated from papermaking in the industry, wherein the lignin content is 10%-20%.

[0014] In step (1), the silicon source includes industrial water glass, sodium silicate, tetraethyl orthosilicate and silicon-containing products after rice husk pyrolysis; preferably, the mass ratio of lignin or its salt to silicon oxide in the silicon source is controlled to be 0.2-2:1.

[0015] In step (1), the surfactant includes hexadecyltrimethylammonium bromide, polyethylene glycol, and sodium dodecylbenzenesulfonate; preferably, the mass ratio of the surfactant to the silicon source is 1:20-40.

[0016] In step (1), the alcohol is a C1-C6 alcohol, preferably ethanol; preferably, the mass ratio of the alcohol to the silicon source is 1-5:1; if the amount of ethanol is too low, the surface of the composite product will be too rough, and if the content is high, it will lead to the aggregation of silicon dioxide.

[0017] In step (1), the mass-to-volume ratio of the alcohol to water is 1g:2-10mL.

[0018] In step (1), the acid precipitation is first carried out at pH 9-10, and then at pH 2-4. Preferably, the acid precipitation temperature is 30-80℃, preferably the temperature of the first acid precipitation is 30-50℃ and the temperature of the second acid precipitation is 50-80℃, and the temperature of the first acid precipitation is lower than the temperature of the second acid precipitation. Preferably, the time of the first acid precipitation and the second acid precipitation are independently selected from 1-3h.

[0019] Through a two-step acid precipitation process, the silicon source will be converted into silicon oxide in solution at a pH of 9-10, serving as the core silicon in the lignin / silicon composite material. When the pH reaches 2-4, lignin will precipitate out and coat the surface of the silicon oxide to form the lignin / silicon composite material.

[0020] The acid precipitation is performed using 15-25 wt% hydrochloric acid, preferably 20 wt%; or 1-10 wt% sulfuric acid, preferably 5 wt%. The hydrochloric acid or sulfuric acid is added dropwise at a rate of 3-5 ml / min; the stirring speed is controlled at 300-500 r / min, as too low or too high a stirring speed will lead to uneven lignin and silica composite.

[0021] The use of different types of acids during acid precipitation will cause the product to appear in different forms. Under hydrochloric acid precipitation, the lignin / silicon composite material will precipitate in the form of a precipitate, while under sulfuric acid precipitation, the lignin / silicon composite material will exist in the form of a gel, and at low temperatures, it will exist in the form of a paste.

[0022] In some embodiments, step (1) involves mixing a lignin alkaline solution with a silicon source aqueous solution, adding an ethanol aqueous solution and a surfactant to obtain a mixed solution containing lignin or its salt, a silicon source, a surfactant, an alcohol, and water, performing acid precipitation to obtain a lignin / silicon precipitate or paste material, and washing and drying to obtain a lignin / silicon nanocomposite material.

[0023] The lignin alkaline solution contains 2-15 wt% solids, preferably 5-10 wt%.

[0024] The pH of the mixed solution is 11-12, preferably adjusted by an aqueous solution of NaOH, and more preferably by an aqueous solution of 30-50 wt% NaOH.

[0025] The washing process involves acid washing the lignin / silicon precipitate or paste with a hydrochloric acid solution of 0.5-2 mol / L, followed by drying to obtain lignin / silicon nanomaterials. Preferably, the washing process uses a hydrochloric acid solution of 0.1-1 mol / L to wash the lignin / silicon precursor. The acid concentration should not be too high, as it may damage the resulting lignin / silicon composite structure. The main purpose is to wash away impurities such as salts and other substances generated in the solution.

[0026] In step (2), the carbonization temperature is 500-1000℃, preferably 700-900℃; preferably, the temperature is increased to the carbonization temperature at a rate of 5-15℃ / min; preferably, the carbonization time is 0.5-4h, preferably 2-3h.

[0027] In a second aspect, the present invention discloses a lignin-carbon / silicon nanocomposite material prepared by the method described in the first aspect above.

[0028] Thirdly, the present invention discloses the application of the above-mentioned lignin carbon / silicon nanocomposite material in reinforcing rubber, such as its application as a reinforcing material in rubber composite materials.

[0029] The rubber mentioned includes natural rubber and / or styrene-butadiene rubber.

[0030] The weight ratio of the lignin carbon / silicon nanocomposite material to rubber is 30-50:100.

[0031] The preparation process of the rubber composite material also includes other auxiliary materials, such as stearic acid, oxidizing agent, vulcanizing agent, vulcanization accelerator, etc.; the vulcanizing agent includes, but is not limited to, sublimed sulfur; the vulcanization accelerator includes DM and / or CZ.

[0032] The weight ratio of the rubber to other auxiliary materials is 100:8-15.

[0033] The preparation method of the rubber composite material is to mix rubber, add auxiliary materials and mix, and then add lignin carbon / silicon nanocomposite material and mix to obtain the final product.

[0034] This invention uses lignin or its salts as raw materials, and combines them with a silicon source through a two-step acid precipitation process, followed by carbonization to prepare a bio-based lignin-carbon / silicon nanocomposite material. The lignin-carbon / silicon nanocomposite material is uniform in size, easy to disperse, and has a strong structural bond, which inhibits the aggregation between lignin and silicon oxide. At the same time, after carbonization, the advantages of bio-based carbon and silicon in rubber are perfectly reflected, which is manifested in the comprehensive properties of rubber such as mechanical properties and antioxidant properties. It can be added to rubber as a substitute for traditional carbon black or silica and applied accordingly.

[0035] Beneficial effects:

[0036] The technical solution provided by this invention utilizes a method for preparing lignin-carbon / silicon nano-reinforcing fillers by combining lignin with silicon sources. The preparation process is simple and the production cost is low. The resulting bio-based carbon / silicon reinforcing filler has advantages such as small particle size, uniform dispersion, and compact structure. When added to rubber, it interacts with the rubber to improve the mechanical properties of the rubber, achieving a reinforcing effect similar to that of silica, which is more conducive to application and promotion. Attached Figure Description

[0037] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0038] Figure 1 This is a laser particle size distribution of the lignin / silicon composite material obtained in Example 1.

[0039] Figure 2 This is a scanning electron microscope image of the lignin / silicon composite material obtained in Example 1.

[0040] Figure 3 This is a laser particle size distribution of the bio-based lignin carbon / silicon nanomaterials obtained in Example 1.

[0041] Figure 4 This is a scanning electron microscope image of the bio-based lignin carbon / silicon nanomaterials obtained in Example 1. Detailed Implementation

[0042] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; unless otherwise specified, the reagents and materials are commercially available.

[0043] Unless otherwise specified, the grinding described in the following examples refers to grinding to below 10 micrometers using a planetary ball mill.

[0044] In the following examples, the concentration of hydrochloric acid is 20 wt%, and the concentration of sulfuric acid is 5 wt%.

[0045] The industrial water glass described in the following examples is sodium silicate nonahydrate, with the chemical formula: Na2SiO3·9H2O.

[0046] The vulcanizing agent described in the following examples is sulfur powder, and the vulcanization accelerator is DM (2,2'-dithiodibenzothiazole).

[0047] The method for preparing rice husk ash silica in the following embodiments is as follows: rice husks are calcined, then successively soaked and washed with hydrochloric acid, boiled with NaOH, and the filter residue is washed with boiling water. HCl is added dropwise to the filtrate to form a gel, which is then dried and ground to form rice husk ash nano-silica. Optimal conditions: hydrochloric acid concentration of 1.3 mol / L, acid soaking time of 24 h, combustion temperature of 600 °C, and combustion time of 5 h.

[0048] Example 1

[0049] Weigh 10g of alkali lignin and dissolve it in 100g of water. Add sodium hydroxide to prepare an alkaline solution with 10% lignin solids. Then, dissolve 35g of industrial water glass in 300g of deionized water. After dissolution, mix the two solutions in a beaker, maintaining the pH of the reaction system within the range of 11-12. Place the stirrer vertically in the beaker and stir at 500 rpm. Then, add 100g of ethanol and 1g of polyethylene glycol 2000 to the solution to aid in the dispersion of lignin and silica. Stir in a 45℃ water bath for 30 minutes to ensure the solution is homogeneous. Add sulfuric acid dropwise to the reaction solution at a uniform rate to induce uniform precipitation of silica until the pH reaches 9.2. Maintain the reaction for 2 hours to complete the first step of acid precipitation. After 2 hours of reaction, raise the reaction temperature to 75℃ and heat for 30 minutes to carry out the second step of acid precipitation. Similarly, use sulfuric acid to adjust the pH to 2 to complete the lignin coating. Let the composite solution stand for 2 hours to facilitate better composite formation of lignin and silica. After the reaction is cooled to room temperature, the solution is washed, dried, and ground to obtain lignin / silicon nanocomposite material.

[0050] The lignin / silicon nanocomposite material was placed in a corundum ceramic boat and carbonized in a carbonization furnace. The optimal carbonization conditions were: under nitrogen protection, the temperature was increased from room temperature at a rate of 10℃ / min for 80 min, then increased to 800℃ and held for 2 h, followed by natural cooling. After grinding, the lignin-carbon / silicon nanocomposite material was obtained.

[0051] The morphology and structure of lignin / silicon nanocomposites and lignin-carbon / silicon nanocomposites were observed using transmission electron microscopy (TEM, JEOL-2100, Hokkaido, Japan) and scanning electron microscopy (FESEM, Regulus 8220, Japan).

[0052] like Figure 1 and Figure 2 As shown, the lignin / silicon composite material obtained from the reaction is uniformly dispersed, has a regular shape, and a diameter of approximately 600 nm. Figure 3 and Figure 4 As shown, the lignin-carbon / silicon composite material is spherical. The lignin exists in the form of carbon after high temperature, and is evenly distributed with a particle size of about 500nm, which is close to the particle size standard of traditional carbon black or white carbon black in rubber.

[0053] The composite material is added to the rubber by weight, and the specific raw material composition is as follows:

[0054] Natural rubber 40g, lignin carbon / silicon nanocomposite material 16g, stearic acid 1.2g, zinc oxide 2g, vulcanizing agent 1g, accelerator 0.24g.

[0055] The rubber compounding process involves the following steps:

[0056] Internal mixing process: The initial mixing temperature is set to 60℃, and the speed of the internal mixer is adjusted to 60r / min. Natural rubber is put into the internal mixer and mixed for 1min. Then zinc oxide and stearic acid are added together and mixed for 2min. The lignin carbon / silicon nanocomposite material is added in two batches (2 / 3 of the total mass in the first batch and the remaining 1 / 3 in the second batch, with an interval of 2min). Each batch is mixed for 2min and then the rubber is discharged.

[0057] The process involves adding vulcanizing agent and vulcanization accelerator DM, performing two tappings, three triangular wrappings, and three rollings to produce rubber composite materials.

[0058] Example 2

[0059] Weigh 100g of papermaking black liquor and, after treatment, prepare an alkaline solution with 10% lignin solids. Then, dissolve 35g of industrial water glass in 300g of deionized water. After dissolution, mix the two solutions in a beaker, maintaining the pH of the reaction system within the range of 11-12. Place the stirrer vertically in the beaker and stir at 500 rpm. Add 100g of ethanol and 1g of polyethylene glycol 2000 to the solution to aid in the dispersion of lignin and silica. Stir in a 45℃ water bath for 30 minutes to ensure homogeneity. Add hydrochloric acid dropwise to the reaction solution at a uniform rate to induce uniform precipitation of silica until the pH reaches 10.5. Maintain the reaction for 2 hours to complete the first step of acid precipitation. After 2 hours, raise the reaction temperature to 75℃ and heat for 30 minutes for the second step of acid precipitation. Again, adjust the pH to 2 using hydrochloric acid to complete the lignin coating. Let the composite solution stand for 2 hours to facilitate better composite formation of lignin and silica. After the reaction is cooled to room temperature, the solution is washed, dried, and ground to obtain lignin / silicon nanocomposite material.

[0060] The lignin / silicon nanocomposite material was placed in a corundum ceramic boat and carbonized in a carbonization furnace. The optimal carbonization conditions were: under nitrogen protection, the temperature was increased from room temperature at a rate of 10℃ / min for 80 min, then increased to 800℃ and held for 2 h, followed by natural cooling. After grinding, the lignin-carbon / silicon nanocomposite material was obtained.

[0061] The composite material is added to the rubber by weight, and the specific raw material composition is as follows:

[0062] Natural rubber 40g, lignin carbon / silicon nanocomposite material 16g, stearic acid 1.2g, zinc oxide 2g, vulcanizing agent 1g, accelerator 0.24g.

[0063] The rubber compounding process involves the following steps:

[0064] Internal mixing process: The initial mixing temperature is set to 60℃, and the speed of the internal mixer is adjusted to 60r / min. Natural rubber is put into the internal mixer and mixed for 1min. Then zinc oxide and stearic acid are added together and mixed for 2min. The lignin carbon / silicon nanocomposite material is added in two batches (2 / 3 of the total mass in the first batch and the remaining 1 / 3 in the second batch, with an interval of 2min). Each batch is mixed for 2min and then the rubber is discharged.

[0065] The process involves adding vulcanizing agent and vulcanization accelerator DM, performing two tappings, three triangular wrappings, and three rollings to produce rubber composite materials.

[0066] Example 3

[0067] 10g of sulfate lignin was dissolved in 100g of water, and sodium hydroxide was added to prepare an alkaline solution with a lignin solids content of 10%. Then, 35g of industrial water glass was dissolved in 300g of deionized water. After dissolution, the two solutions were mixed in a beaker, maintaining the pH of the reaction system within the range of 11-12. The stirrer was placed vertically in the beaker, and the stirring speed was 500 rpm. Then, 100g of ethanol and 2g of sodium dodecylbenzenesulfonate were added to the solution to aid in the dispersion of lignin and silica. The mixture was stirred in a 45℃ water bath for 30 minutes to ensure homogeneity. Hydrochloric acid was added dropwise to the reaction solution at a uniform rate to induce uniform precipitation of silica until the pH reached 10.5. The reaction was maintained for 2 hours to complete the first step of acid precipitation. After 2 hours of reaction, the reaction temperature was increased to 50℃ and heated for 30 minutes for the second step of acid precipitation. Hydrochloric acid was used to adjust the pH to 4 to complete the lignin coating. The composite solution was then allowed to stand for 2 hours to facilitate better composite formation of lignin and silica. After the reaction is cooled to room temperature, the solution is washed, dried, and ground to obtain lignin / silicon nanocomposite material.

[0068] The lignin / silicon nanocomposite material was placed in a corundum ceramic boat and carbonized in a carbonization furnace. The optimal carbonization conditions were: under nitrogen protection, the temperature was increased from room temperature at a rate of 10℃ / min for 80 min, then increased to 800℃ and held for 2 h, followed by natural cooling. After grinding, the lignin-carbon / silicon nanocomposite material was obtained.

[0069] Example 4

[0070] Weigh 10g of calcium lignin sulfonate and dissolve it in 100g of water. Add sodium hydroxide to prepare an alkaline solution with 10% lignin solids. Then, dissolve 20g of rice husk ash silica in 200g of deionized water using ultrasonication. Mix the two solutions in a beaker, maintaining the pH of the reaction system within the range of 11-12. Place the stirrer vertically in the beaker and stir at 500 rpm. Add 100g of ethanol and 2g of sodium dodecylbenzene sulfonate to the solution to aid in the dispersion of lignin and silica. Stir in a 40℃ water bath for 30 minutes to ensure the solution is homogeneous. Add hydrochloric acid dropwise to the reaction solution at a uniform rate to precipitate silica evenly until the pH reaches 10.5. Maintain the reaction for 2 hours to complete the first step of acid precipitation. After 2 hours of reaction, raise the reaction temperature to 75℃ and heat for 30 minutes to carry out the second step of acid precipitation. Similarly, adjust the pH to 4 using hydrochloric acid to complete the lignin coating. Let the composite solution stand for 2 hours to facilitate better composite formation of lignin and silica. After the reaction is cooled to room temperature, the solution is washed, dried, and ground to obtain lignin / silicon nanocomposite material.

[0071] The lignin / silicon nanocomposite material was placed in a corundum ceramic boat and carbonized in a carbonization furnace. The optimal carbonization conditions were: under nitrogen protection, the temperature was increased from room temperature at a rate of 10℃ / min for 80 min, then increased to 800℃ and held for 2 h, followed by natural cooling. After grinding, the lignin-carbon / silicon nanocomposite material was obtained.

[0072] Comparative Example 1

[0073] The composite material is added to the rubber by weight, and the specific raw material composition is as follows:

[0074] Natural rubber 40g, lignin 16g, stearic acid 1.2g, zinc oxide 2g, vulcanizing agent 1g, accelerator 0.24g.

[0075] The rubber compounding process involves the following steps:

[0076] Internal mixing process: The initial mixing temperature is set to 60℃, the speed of the internal mixer is adjusted to 60r / min, natural rubber is put into the internal mixer and mixed for 1min, then zinc oxide and stearic acid are added together and mixed for 2min, lignin is added in two batches and mixed for 2min each time, and then the rubber is discharged.

[0077] The process involves adding vulcanizing agent and vulcanization accelerator DM, performing two tappings, three triangular wrappings, and three rollings to produce rubber composite materials.

[0078] Comparative Example 2

[0079] The composite material is added to the rubber by weight, and the specific raw material composition is as follows:

[0080] Natural rubber 40g, silica 16g, coupling agent Si-69 1.6g, stearic acid 1.2g, zinc oxide 2g, vulcanizing agent 1g, accelerator 0.24g.

[0081] The rubber compounding process involves the following steps:

[0082] Internal mixing process: The initial mixing temperature is set to 60℃, and the speed of the internal mixer is adjusted to 60r / min. Natural rubber is put into the internal mixer and mixed for 1min. Then zinc oxide and stearic acid are added together and mixed for 2min. Silica and coupling agent Si-69 are added in two batches and mixed for 2min each. The rubber is then discharged.

[0083] The process involves adding vulcanizing agent and vulcanization accelerator DM, performing two tappings, three triangular wrappings, and three rollings to produce rubber composite materials.

[0084] Comparative Example 3

[0085] Weigh 10g of alkali lignin and dissolve it in 100g of water. Add sodium hydroxide to prepare an alkaline solution with 10% lignin solids. Then, dissolve 35g of industrial water glass in 300g of deionized water. After dissolution, mix the two solutions in a beaker, maintaining the pH of the reaction system within the range of 11-12. Place the stirrer vertically in the beaker and stir at 500 rpm. Then, add 100g of ethanol and 1g of polyethylene glycol 2000 to the solution to aid in the dispersion of lignin and silica. Stir in a 45℃ water bath for 30 minutes to ensure the solution is homogeneous. Add sulfuric acid dropwise to the reaction solution at a uniform rate to induce uniform precipitation of silica until the pH reaches 9.2. Maintain the reaction for 2 hours to complete the first step of acid precipitation. After 2 hours of reaction, proceed with the second step of acid precipitation. Similarly, use sulfuric acid to adjust the pH to 2 to complete the lignin coating. Let the composite solution stand for 2 hours to facilitate better composite formation of lignin and silica. After the reaction is cooled to room temperature, the solution is washed, dried, and ground to obtain lignin / silicon nanocomposite material.

[0086] The lignin / silicon nanocomposite material was placed in a corundum ceramic boat and carbonized in a carbonization furnace. The optimal carbonization conditions were: under nitrogen protection, the temperature was increased from room temperature at a rate of 10℃ / min for 80 min, then increased to 800℃ and held for 2 h, followed by natural cooling. After grinding, the lignin-carbon / silicon nanocomposite material was obtained.

[0087] The composite material is added to the rubber by weight, and the specific raw material composition is as follows:

[0088] Natural rubber 40g, lignin carbon / silicon composite material 16g, stearic acid 1.2g, zinc oxide 2g, vulcanizing agent 1g, accelerator 0.24g.

[0089] The rubber compounding process involves the following steps:

[0090] Internal mixing process: The initial mixing temperature is set to 60℃, the speed of the internal mixer is adjusted to 60r / min, the natural rubber is put into the internal mixer and mixed for 1min, then zinc oxide and stearic acid are added together and mixed for 2min, the lignin carbon / silicon material is added in two batches and mixed for 2min each time, and then the rubber is discharged.

[0091] The process involves adding vulcanizing agent and vulcanization accelerator DM, performing two tappings, three triangular wrappings, and three rollings to produce rubber composite materials.

[0092] The vulcanization time and mechanical properties of the rubber materials obtained in the examples and comparative examples are shown in Tables 1 and 2.

[0093] Table 1 Comparison of vulcanization time of traditional rubber materials in Examples 1 & 2 and Comparative Examples 1-3

[0094]

[0095] As shown in Table 1, the vulcanization time Tc90 of Example 1 (lignin carbon / silicon nanocomposite material) is significantly reduced compared to Comparative Example 2 (silica). Compared to Comparative Example 3, increasing the reaction temperature effectively enhances the efficient synthesis of lignin and silica, thus increasing the vulcanization efficiency. A comparison with the vulcanization time of Comparative Example 1 (proto-lignin) shows that lignin can significantly improve the vulcanization rate through carbonization composite processing. In Examples 1 and 2, M... H Compared with Comparative Example 1 (lignin), the difference is significantly higher, indicating that the degree of cross-linking is increased. The lignin carbon / silicon nanomaterials formed after carbonization form a denser cross-linking network with the rubber molecular chains.

[0096] Table 2 Comparison of mechanical property tests of traditional rubber materials in Examples 1 & 2 and Comparative Examples 1 & 2

[0097]

[0098] Table 2 compares the mechanical properties of Examples 1 and 2 with Comparative Example 2. The tensile properties of Examples 1 and 2 are similar, with Example 1 even outperforming Comparative Example 2 (white carbon black) by approximately 1 MPa, showing a significant improvement in mechanical properties. Compared to Comparative Example 1 (original lignin), it is evident that the carbon / silicon composite material significantly enhances the mechanical properties of the rubber after carbonization. Compared to Comparative Example 3, the high dispersion of lignin and silica is clearly reflected in the mechanical properties after carbonization, exceeding them by approximately 2-3 MPa. Similarly, different pH controls during the reaction can lead to a decrease in the final performance.

[0099] This invention provides a lignin-carbon / silicon nanomaterial and its preparation method, achieving the goals of reducing the cost of rubber reinforcing fillers, minimizing the use of petroleum resources, and addressing the issues of efficient lignin utilization and environmental pollution. The method employs a two-step acid precipitation process to prepare a lignin / silicon composite, followed by carbonization to form the lignin-carbon / silicon nanomaterial. The lignin-carbon / silicon nanomaterial prepared by this method is primarily a silicon / carbon composite material with silicon as the core and lignin-carbon as the shell encapsulating the silicon surface. The tight bonding between carbon and silicon results in advantages such as good reinforcing effect, uniform particle size, and easy dispersion, improving the mechanical properties of the material and facilitating its application and promotion.

[0100] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. The application of a lignin-carbon / silicon nanocomposite material as a reinforcing material in rubber composites, characterized in that, The preparation method of the lignin-carbon / silicon nanocomposite material includes: (1) A mixed solution containing lignin or its salt, silicon source, surfactant, alcohol and water is first acid-precipitated at pH 9-10, and then acid-precipitated at pH 2-4 to obtain lignin / silicon nanocomposite material; the silicon source is a substance containing silicon oxide; the temperature of the first acid precipitation is 30-50℃, the temperature of the second acid precipitation is 50-80℃, and the temperature of the first acid precipitation is lower than the temperature of the second acid precipitation; (2) The obtained lignin / silicon nanocomposite material is carbonized to obtain lignin carbon / silicon nanocomposite material; In step (1), the mass ratio of lignin or its salt to silicon oxide in the silicon source is controlled to be 0.2-2:1; the mass ratio of the surfactant to the silicon source is 1:20-40; the mass ratio of the alcohol to the silicon source is 1-5:1; and the mass-volume ratio of the alcohol to water is 1g:2-10mL.

2. The application according to claim 1, characterized in that, In step (1), the silicon source includes industrial water glass, sodium silicate, tetraethyl orthosilicate and silicon-containing products from the pyrolysis of rice husk.

3. The application according to claim 1, characterized in that, In step (1), the surfactant includes hexadecyltrimethylammonium bromide, polyethylene glycol, and sodium dodecylbenzenesulfonate.

4. The application according to claim 1, characterized in that, In step (1), the alcohol is a C1-C6 alcohol.

5. The application according to claim 1, characterized in that, In step (1), the alcohol is ethanol.

6. The application according to claim 1, characterized in that, In step (1), the acid precipitation is carried out using 15-25wt% hydrochloric acid or 1-10wt% sulfuric acid; the time for the first acid precipitation and the second acid precipitation are independently selected from 1-3h.

7. The application according to claim 1, characterized in that, In step (2), the carbonization temperature is 500-1000℃; the carbonization time is 0.5-4h.

8. The application according to claim 1, characterized in that, In step (2), the carbonization temperature is 700-900℃.

9. The application according to claim 1, characterized in that, In step (2), the temperature is increased to the carbonization temperature at a rate of 5-15℃ / min.

10. The application according to claim 1, characterized in that, The weight ratio of the lignin carbon / silicon nanocomposite material to rubber is 16:30-50.

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